Slacken/ˈslækən/ Definition 1 of 3Pro Tip 1/3Emotional Impact Used to show easing of emotions or intensity in various situations. The harsh weather began to slacken, bringing relief to the stranded hikers. Pro Tip 2/3Gradual Change Describes a process that occurs slowly, not suddenly. As the night advanced, the winds slackened, making it easier to set up camp. Pro Tip 3/3Physical Easing Can refer to literally loosening physical tightness, like a knot. She had to slacken the rope to free her trapped puppy.